Delgine Project -
This project focuses on the development of 3D game development tools.

Dryad -
lets you intuitively create beautiful trees for your virtual world or game. Unfortunately "The Dryad software and related source code for collaborative design space exploration are now available upon request."

Paint.NET - image and photo manipulation software designed to be used on computers that run Windows. It supports layers, unlimited undo, special effects, and a wide variety of useful and powerful tools.